// Import types
import type { ReadingPosition } from "./types";
import { findPageByCFI, createPositionFromPage } from "./page-calculator";
import { UniversalReader } from "../../reader-shell";

// Update current position
export function updateCurrentPosition(
  book: UniversalReader,
  position: ReadingPosition,
): UniversalReader {
  return {
    ...book,
    position,
  };
}

// Extract CFI from position
export function getCurrentCFI(book: UniversalReader): string {
  return book.position.cfi;
}

// Calculate progress for display
export function calculateProgress(book: UniversalReader): {
  currentPage: number;
  totalPages: number;
  percentage: number;
} {
  const totalPages = book.pagination?.totalPages || 1;
  const currentPage = book.position.currentPage;
  const percentage =
    totalPages > 0 ? Math.round((currentPage / totalPages) * 100) : 0;

  return { currentPage, totalPages, percentage };
}

// Get position for saving to database
export function getPositionForSave(book: UniversalReader): {
  cfi: string;
  progress: number;
  page: number;
} {
  return {
    cfi: book.position.cfi,
    progress: book.position.progress,
    page: book.position.currentPage,
  };
}

// Restore position from database
export function restorePosition(
  book: UniversalReader,
  savedCFI: string,
  savedPage?: number,
): ReadingPosition {
  if (!book.pagination) {
    return book.position;
  }

  // If we have saved CFI, try to find exact position
  if (savedCFI) {
    const pageNum = findPageByCFI(book.pagination, savedCFI);
    return createPositionFromPage(book, pageNum);
  }

  // Otherwise use saved page number
  if (savedPage && savedPage > 0) {
    return createPositionFromPage(book, savedPage);
  }

  return book.position;
}

// Check if position changed significantly
export function didPositionChange(
  oldPos: ReadingPosition,
  newPos: ReadingPosition,
): boolean {
  return (
    oldPos.currentPage !== newPos.currentPage ||
    oldPos.cfi !== newPos.cfi ||
    Math.abs(oldPos.progress - newPos.progress) > 0.01
  );
}